The invention relates to apparatus for temperature measurement and more particularly for measurement of relative transfer of radiant or thermal energy through a transparent panel, such as window.
Thermometers of various types have been provided for sensing and displaying the temperature inside or outside of a building. In some cases, such thermometers include temperature sensing elements which can be positioned respectively inside and outside the window of a room, with the sensing elements connected to respective temperature indicators positioned side-by-side for convenient comparison at a location inside such a room, as in the case of so-called "indoor-outdoor thermometers."
In recent years, there has been increasing emphasis on the conservation of thermal energy in order to minimize the excessive use of scarce heating fuels for homes and other buildings and to maximize the use of solar energy for as much heating as possible. The use of window drapes has been suggested as a means for helping to prevent undesired loss of heat from the interior of a room through the windows of such a room. Such drapes adversely reduce the radiation of solar energy from the outside of the building into the room through such a window, if the drapes are closed when there is adequate external thermal radiation striking and passing through the window. In many cases, however, it is difficult to know whether the level of incoming solar or radiant energy is great enough to provide a temperature within the room which would be higher than or help maintain the interior room temperature, or whether such solar energy is insufficient to maintain the window surface at a temperature which would assist in maintaining the desired interior temperature with the curtains, drapes or blinds open, or whether such screening elements should be closed to minimize any undesired heat transfer one way or the other through such a window.